Since short and long-term morbidity and mortality are closely related to the functional defect produced by acute myocardial infarction, it is our purpose to carefully quantitate this functional defect using serial gated radioangiography in both dogs and patients following myocardial infarction. Volumes and segmental wall motion will be used to quantitate the global and regional defects produced by the acute infarction. Comparison with other methods for measuring infarct size (CPK curves, pyrophosphate scans, precordial electrocardiography, perfusion imaging, hemodynamics, and clinical course) will be utilized to define the usefulness of serial radioangiography. In dogs, wall motion studies will also be performed with the use of implanted tantalum screws and serial cine strips. A comparison of the above techniques with pathologic infarct size in the dog will be used as an absolute standard. A new Germanium camera with an improved spatial resolution of three to five times, and an improved energy resolution of five to seven times, will be used in years two and three, and should markedly enhance the precision of all the measurements obtained. Overall, it is anticipated that the information obtained regarding functional infarct size (serial radioangiography) and anatomic infarct size (the other techniques listed) will be of great value in assessing the overall effect of the myocardial infarction, and should relate closely to short-term morbidity and mortality.